The activating effect of oxygen depletion at the cathode was already recognized by scientists in Los Alamos in the United States and recently published by Christian Eickes, Piotr Piela, John Davey and Piotr Zelenay, “Recoverable Cathode Performance Loss in Direct Methanol Fuel Cells”, Journal of The Electrochemical Society, 153/1 (2006) A171-A178.
The method described there as the “air break” method functions in a sequence of four consecutive steps: 1) stopping the air feed on the cathode side, 2) immediately switching over to a galvanostatic mode of operation in which the same current is set that was being generated at the moment of the switching over, 3) switching on the air feed as soon as a critical minimum cell tension has been reached, 4) immediately switching over to the potentiostatic mode of operation.
In their experiment, Eickes el al. (see above) apply the activation method every 10 minutes, and interrupt the air flow for 13 seconds each time. The current density and thus the cell performance rise by about 15% after each activation under the applicable test conditions. The authors ascribe the activation effect to a reduction of the platinum oxide at the cathode that forms on the surface of the catalyst during the fuel cell operation and impairs the catalysis of the oxygen reduction. The reduction takes place due to the low cathode potential during the activation period of 13 seconds.
In this publication, no statements are made about an electrolysis regimen or about a bi-functional regimen, nor are any possible activation effects due to electrolysis discussed.